1. Field of the Invention
The invention relates in general to a multi-layer printed circuit board wiring layout and method for manufacturing the same, and more particularly to a multi-layer printed circuit board wiring layout having a slanting via and method for manufacturing the same.
2. Description of the Related Art
The wiring layout on the circuit board of a mobile phone becomes more and more complicated as more and more functions are added. Normally, different wire layers are connected by a via, such as a barrier via, a blind via or a through via, through which signals are transmitted between different wire layers. The following disclosure is exemplified by the via connecting two wire layers.
Referring to FIG. 1A, a structural diagram of a conventional mobile phone printed circuit board having a via is shown. Printed circuit board 100 at least includes a first wire layer 110, a second wire layer 120, a dielectric layer 130 and a via 140 connecting the first wire layer 110 and the second wire layer 120. The first wire layer 110 includes a first wiring 112, and the second wire layer 120 includes a second wiring 122. The via 140 has an electroplated layer (not shown in the diagram) electroplated within to conduct the first wiring 112 and the second wiring 122.
The direction K of the via 140 is perpendicular to the first wire layer 110 and the second wire layer 120, so that the signal S bends at 90° when entering the via 140 from the second wiring 122 at first and then again bends at 90° when entering the first wiring 112 after passing through the via 140. As shown in FIG. 1B, the signal S passes on the second wiring 122 with a wire-width of W1. When the signal S passes through the second wiring 122 the wire-width changes to W2 (W2>W1) at the corner of the via 140 where the second wiring 122 is connected to the electroplated layer 142. The wiring resistance is inversely proportional to the cross-section area of the wiring. Therefore, the cross-section area of the wiring suddenly increases at bending area C and returns to its original size after passing through the bending area C. Consequently, the signal S and adjacent signals as well are easily interfered with by the resistance change of the wiring. Particularly, the higher the frequency of the signal S is, the larger the interference will be, severely affecting the quality of signal transmission between different wire layers.